This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The FIRST (Functional Imaging Research Schizophrenia Testbed) Biomedical Informatics Research Network (fBIRN) program is the first-ever large scale, multi-center fMRI study of schizophrenia (http://www.nbirn.net). The fBIRN project will pool fMRI data from each of the 11 participating sites to enable the acquisition of a large and diverse study population in a modest time period. Our Center has been responsible for the calibration and quality assurance aspects important for multi-center fMRI trials, and G. Glover chairs the Calibration Working Group within the fBIRN. This subproject is a study of the use of breath holding (BH) to calibrate and mitigate the confounding effects of hemodynamic differences between subjects, thereby reducing variance and improving the ability to pool data across large populations. Previous activities have developed the basic method, which is in current use by the consortium.